Flutter: LateInitializationError after resizing of the widget

I get a LateInitializationError on items_head after resizing my widget.

This is code:

class Head_View extends StatefulWidget {
  Head_View({Key? key}) : super(key: key);
  late List<AppointmentItemWrapper> items_head;
  //late MultiChildRenderObjectWidget DTIT_head; --> **EDIT ON 20230605**
  @override
  State<Head_View> createState() => _Head_ViewState();
}

class _Head_ViewState extends State<Head_View> {
  @override
  void initState() {

    widget.items_head = [
      AppointmentItemWrapper(
        ID: 111,
        key: UniqueKey(),
        startDateTime: DateTime(2022, 1, 1, 8, 00, 0),
        endDateTime: DateTime(2022, 1, 1, 9, 30,0),
        position: 0,
        text: "Event N1",
        positiondragging: (double valxx) { print("HAHAH"); },
      ),
    ];

    super.initState();
  }

  @override
  Widget build(BuildContext context) {

    return DynamicTimeline(
      key: _myWidgetKey_DTIT_head,
      firstDateTime: DateTime(2022, 1, 1,7,0,0),
      lastDateTime: DateTime(2022, 1, 1,18,0,0),
      labelBuilder: DateFormat('hh:mm').format,
      items: widget.items_head, );
  }
}

As I thought:

initState() should be normally only called before first build (first build would happen in super.init()? )and when resizing the widget, build should be called again to rebuild the widget, but the items_head should be already in scope or am I wrong?